Processing and characterization of sinter-crystallized basalt glass-ceramics

• Published in: Journal of non-crystalline solids 2020-06, Vol.538, p.120019, Article 120019
• Main Authors: Lima, Luiza F., Mantas, Pedro Q., Segadães, Ana M., Cruz, Robinson C.D.
• Format: Article
• Language: English
• Subjects: Basalt; Glass-ceramics; Sinter-crystallization
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2020.120019

•Paper explores the sinter-crystallization of basalt glass frits for glass-ceramics.•Intermediate isothermal steps had no relevant effect on the final microstructure.•Final heat treatment temperature determines the glass-ceramic microstructure.•Short heat treatment at the final temperature leads to comparable property values.•Nucleation is a very fast process and crystal growth is rather limited. In this work, basalt from the Serra Geral Formation, Brazil, was used to prepare a glass frit from which glass-ceramics were produced by the sinter-crystallization process. After different heat treatments in an inert atmosphere, properties were evaluated, as well as their relationship with the obtained microstructure. The results show that bulk density, hardness and crystallinity index increased with the treatment time up to the final temperature, with highest values for the longest heat treatment (6.5 h), respectively 2.39 g/cm3, 74.8% and 9.81 GPa. However, a shorter heat treatment (2.5 h) at the same final temperature resulted in comparable values (respectively, 2.38 g/cm3, 72.3% and 9.68 GPa). As such, isothermal steps at intermediate crystallization temperatures have no relevant influence on the final microstructure. Thus, for this basalt, nucleation is a very fast process and crystal growth is likely rather limited and little improved by intermediate crystallization heat treatment steps.